[Ocfs2-devel] [PATCH 0/40] ocfs2: Detach ocfs2 metadata I/O from struct inode

[Joel Becker]

The following series of patches attempts to detach metadata I/O from
struct inode.   They are currently tied together pretty tightly.
Metadata reads happen via the ocfs2_read_blocks() functions, writes via
both jbd2 and ocfs2_write_blocks().

- Each inode has a cache of associated metadata blocks stored on its
  ip_metadata_cache member.  The ocfs2_read/write_blocks() functions
  take a struct inode to access this member.

- The journal mostly doesn't care about inodes.  It does, however, need
  to set the transaction id on the inode so that dlmglue knows when an
  inode needs to checkpoint.

- All the metadata I/O paths use ip_io_mutex to synchronize their
  actions against each other.

The problem is that if someone wants to use our metadata I/O facilities,
they have to have a struct inode.  But not everything in ocfs2 is an
inode (even if it seems that way sometimes).  So we want to disconnect
them.

It turns out that most of what goes on is about ocfs2_caching_info.  So
if we move the last few relevant bits to ocfs2_caching_info, we can then
embed ocfs2_caching_info into another structure just as easily as we do
inside struct inode.  That's the theory, anyway.

The first three patches move the cache code to ocfs2_caching_info
entirely.  The functions affecting the metadata cache, like
ocfs2_set_buffer_uptodate(), etc, take a struct ocfs2_caching_info
instead of a struct inode.  That sort of thing.  It's nice and easy.

The next three patches move the journal transaction ids to struct
ocfs2_caching_info.  When they are done, the ocfs2_journal_access*()
functions take a stuct ocfs2_caching_info, and the dlmglue checks the
ocfs2_caching_info regarding checkpoints.  So it only takes us six
patches to isolate ocfs2_caching_info in the metadata I/O API.

The remaining 34 patches slowly but surely move alloc.c to the new API.
Our btree code is heavily invested in the idea that all btrees are
rooted, somehow, at an inode.  Since we want to root a btree at a
non-inode, we need to fix that.  The good news, of course, is that the
ocfs2_extent_tree abstraction is already there to rescue us.  We attach
the ocfs2_caching_info to a particular ocfs2_extent_tree, and we can
then send that ocfs2_extent_tree down through the btree code.  At the
end of this series, the generic btree code doesn't reference struct
inode at all.

There are a lot of patches because this entire series is supposed to be
isomorphic.  No behavior is to change, just the flexibility of our API.
Thus, each patch tries to be readily understandable.  Thank you for your
patience!

[View]
http://oss.oracle.com/git/?p=jlbec/linux-2.6.git;a=shortlog;h=cacheme
[Pull]
git://oss.oracle.com/git/jlbec/linux-2.6.git cacheme

Joel Becker (40):
      ocfs2: Make the ocfs2_caching_info structure self-contained.
      ocfs2: Change metadata caching locks to an operations structure.
      ocfs2: Take the inode out of the metadata read/write paths.
      ocfs2: move ip_last_trans to struct ocfs2_caching_info
      ocfs2: move ip_created_trans to struct ocfs2_caching_info
      ocfs2: Pass struct ocfs2_caching_info to the journal functions.
      ocfs2: Store the ocfs2_caching_info on ocfs2_extent_tree.
      ocfs2: Pass ocfs2_caching_info to ocfs2_read_extent_block().
      ocfs2: ocfs2_find_path() only needs the caching info
      ocfs2: ocfs2_create_new_meta_bhs() doesn't need struct inode.
      ocfs2: Pass ocfs2_extent_tree to ocfs2_unlink_path()
      ocfs2: ocfs2_complete_edge_insert() doesn't need struct inode at all.
      ocfs2: Get inode out of ocfs2_rotate_subtree_root_right().
      ocfs2: Pass ocfs2_extent_tree to ocfs2_get_subtree_root()
      ocfs2: Drop struct inode from ocfs2_extent_tree_operations.
      ocfs2: ocfs2_rotate_tree_right() doesn't need struct inode.
      ocfs2: ocfs2_update_edge_lengths() doesn't need struct inode.
      ocfs2: ocfs2_rotate_subtree_left() doesn't need struct inode.
      ocfs2: __ocfs2_rotate_tree_left() doesn't need struct inode.
      ocfs2: ocfs2_rotate_tree_left() no longer needs struct inode.
      ocfs2: ocfs2_merge_rec_left/right() no longer need struct inode.
      ocfs2: ocfs2_try_to_merge_extent() doesn't need struct inode.
      ocfs2: ocfs2_grow_branch() no longer needs struct inode.
      ocfs2: ocfs2_append_rec_to_path() loses struct inode.
      ocfs2: ocfs2_truncate_rec() doesn't need struct inode.
      ocfs2: Make truncating the extent map an extent_tree_operation.
      ocfs2: ocfs2_insert_at_leaf() doesn't need struct inode.
      ocfs2: Give ocfs2_split_record() an extent_tree instead of an inode.
      ocfs2: ocfs2_do_insert_extent() and ocfs2_insert_path() no longer need an 
      ocfs2: ocfs2_extent_contig() only requires the superblock.
      ocfs2: Swap inode for extent_tree in ocfs2_figure_merge_contig_type().
      ocfs2: Remove inode from ocfs2_figure_extent_contig().
      ocfs2: ocfs2_figure_insert_type() no longer needs struct inode.
      ocfs2: Make extent map insertion an extent_tree_operation.
      ocfs2: ocfs2_insert_extent() no longer needs struct inode.
      ocfs2: ocfs2_add_clusters_in_btree() no longer needs struct inode.
      ocfs2: ocfs2_remove_extent() no longer needs struct inode.
      ocfs2: ocfs2_split_and_insert() no longer needs struct inode.
      ocfs2: __ocfs2_mark_extent_written() doesn't need struct inode.
      ocfs2: Pass ocfs2_caching_info into ocfs_init_*_extent_tree().

 alloc.c          |  896 ++++++++++++++++++++++++++++---------------------------
 alloc.h          |   33 --
 aops.c           |   10 
 buffer_head_io.c |   47 +-
 buffer_head_io.h |    8 
 dir.c            |   38 +-
 dlmglue.c        |    4 
 extent_map.c     |   14 
 file.c           |   21 -
 inode.c          |   80 ++++
 inode.h          |   20 -
 journal.c        |   53 +--
 journal.h        |   70 ++--
 localalloc.c     |   12 
 namei.c          |   37 +-
 ocfs2.h          |   38 ++
 quota_global.c   |    5 
 quota_local.c    |   16 
 resize.c         |   16 
 slot_map.c       |   10 
 suballoc.c       |   35 +-
 super.c          |    5 
 uptodate.c       |  265 +++++++++-------
 uptodate.h       |   51 ++-
 xattr.c          |   81 ++--
 25 files changed, 1056 insertions(+), 809 deletions(-)